LEDs are used for illumination in a wide variety of applications. For example, arrays of LEDs may be used as backlights in computer displays, televisions and other displays, some of which may comprise a plurality of individually controllable LEDs as light sources.
LED packages that contain multiple diodes of same or different colors (also referred to as multi-die LED packages) have been developed and have the advantages of reduced volume and manufacturing costs. Multi-die LED packages may be used in backlights of the above mentioned displays to provide high-intensity light, for example.
One problem with using LEDs as light sources is that the amount of light emitted at a specific driving current level can vary significantly between individual LEDs. This variation can result from manufacturing process variations. Further, the amount of light that an individual LED will produce for any given driving current tends to slowly decrease in an unpredictable manner as the LED ages.
Another problem associated with some LEDs is that color temperature of the emitted light can vary between individual LEDs or shift from a designed-for value by various amounts. Such color temperature variation or shift is undesirable in many situations.
The above problems apply to diodes in a multi-die LED package as well. It is therefore desirable to provide a mechanism for correcting for the above problems in a multi-die LED package.
In addition, as display panel sizes and accordingly the backlight unit sizes continue to increase, there exists a need for backlight units that are reliable and cost-efficient to manufacture and repair. In particular, there is a need for backlight units having an integrated optical structure that comprises a plurality of modules.